COLLEGE    OF    AGRICULTURE  benj.  ide  wheeler,  president 

THOMAS    FORSYTH    HUNT,    DEAN    AND    DIRECTOR 


UNIVERSITY  OF  CALIFORNIA  AGRICULTURAL    EXPERIMENT    STATION 

,E    OF    AGRIC 
BERKELEY 

CIRCULAR  No.  86 


OLIVES  IN  CALIFORNIA. 

by 
F.   T.   BIOLETTI. 

Uses.  The  most  profitable  use  of  the  olive  is  the  making  of  ripe 
pickles.  Our  green  pickles,  at  present,  do  not  compete  successfully 
with  those  imported  from  Spain.  Oil  is  made  from  fruit  too  small  for 
pickling,  and  from  that  damaged  by  frost.  It  is  profitable  as  a  by- 
product of  the  pickling  industry. 

Climate.  The  olive  requires  a  warmer  winter  than  the  grape  and 
a  dryer  summer  than  the  orange.  In  California,  the  olive  region 
coincides  very  closely  with  that  of  the  raisin  Muscat.  A  temperature 
of  14°  F.  is  the  lowest  that  most  varieties  can  stand,  even  when  most 
dormant.  The  cocl  ana  foggy  summers  of  the  coast  region  are 
unfavorable. 

Soil.  Any  soil  that  is  well  drained  and  not  too  shallow  will  support 
the  olive.  It  gives  the  best  results  in  moderately  rich,  light  soils,  where 
the  roots  can  penetrate  deeply.  Very  heavy  or  undrained  soils  are 
unsuitable.     Abundant  lime  is  favorable. 

Propagation.  Young  trees  for  planting  may  be  started  from  seed 
or  from  cuttings  taken  from  any  part  of  the  tree.  The  sprouting  of 
the  seeds,  which  is  difficult,  may  be  facilitated  by  soaking  for  several 
hours  in  a  10  per  cent  solution  of  caustic  potash,  or  by  slightly  crush- 
ing the  shell.  Seedlings  are  grafted  in  the  nursery  when  one  or  two 
years  old,  and  are  ready  for  transplanting  the  following  year. 

Most  nurserymen 's  trees  are  raised  from  ' '  tips, ' '  or  the  extreme  ends 
of  the  branches.  These  are  cut  in  the  spring  about  five  inches  long, 
all  the  leaves,  except  the  top  two  or  three,  removed,  and  then  rooted 
in  sandy  loam  under  glass.  -Cuttings  of  any  size  or  age  can  be  rooted 
directly  in  the  nursery,  but  are  difficult  to  start  if  of  smaller  diameter 
than  3  inches. 

Grafting.  Young  seedlings  are  grafted  at  the  surface  of  the  ground. 
Scions  of  two-year-old  wood  are  used.  Cleft,  side  or  tongue  grafting 
will  succeed.  The  grafts  are  tied  with  raffia,  well  waxed  and  covered 
with  soil.  Larger  seedlings  may  be  twig-budded  just  above  the  surface 
of  the  ground.  Old  trees  may  be  crown  grafted  in  the  branches,  or 
twig-budded  in  sprouts  produced  by  cutting  off  the  branches  the  year 
previous.  Grafting  should  be  done  just  before  the  starting  of  the  sap 
in  the  spring,  budding  a  little  later. 


—  2  — 

Care  of  Orchards.  The  olive  requires  the  same  cultural  treatment 
as  other  fruit  trees  in  California.  The  sqil  should  be  ploughed  as 
deeply  as  possible  before  planting.  Hardpan  soil  can  sometimes  be 
made  suitable  by  the  use  of  dynamite.  Thorough  cultivation  and 
sufficient  water  are  necessary.  Irrigations  are  preferably  few  and 
copious. 

Pruning.  During  the  first  five  or  six  years,  the  sole  object  of  pruning 
is  to  direct  the  growth  of  the  plant  into  building  up  a  "skeleton"  of 
proper  form.  This  should  consist  of  a  single,  straight  clean  trunk, 
two  to  three  feet  high,  bearing  on  top  five  or  six  main  branches,  sym- 
metrically placed.  Every  shoot  or  branch,  which  is  not  needed  per- 
manently, should  be  removed  as  soon  as  possible,  in  order  to  avoid  the 
necessity  of  large  wounds.  Twigs  are  left  on  the  trunk  only  so  long 
as  they  are  needed  to  protect  it  from  the  sun. 

In  pruning  bearing  trees,  the  branches  are  first  thinned  sufficiently 
to  allow  light  to  enter  and  promote  annual  growth  in  all  parts.  The 
annual  growth  of  the  preceding  year  is  then  cut  back  about  one  half, 
a  little  more  with  weak  trees,  and  a  little  less  with  strong.  Without 
pruning,  the  crop  is  small  and  poor.  With  irregular  pruning,  the  crop 
is  irregular.  New  growth  is  necessary  each  year  for  annual  crops. 
Pruning  is  the  only  method  of  "thinning"  and  is  essential  for  large 
fruit. 

Harvesting.  The  crops  of  profitable  orchards  vary  from  one  half 
to  four  tons  per  acre.  Large  olives  intended  for  pickling  are  gathered 
carefully  by  hand  into  padded  baskets  or  bags,  hung  on  the  shoulders 
of  the  pickers,  and  hauled  to  the  factory  in  barrels  containing  water. 
The  cost  varies  considerably  with  the  size  of  the  olives  and  of  the  crop 
and  averages  about  $15  per  ton. 

Oil  olives  are  preferably  gathered  in  the  same  way,  but  are  often 
shaken  and  raked  off  the  tree  and  collected  in  sheets  spread  on  the 
ground.  Unless  the  olives  can  be  worked  immediately,  this  method 
gives  inferior  oil. 

Diseases.  The  only  serious  disease  infecting  the  olive  in  California 
is  the  olive  knot,  which  does  much  harm  only  to  young  trees,  or  to  trees 
in  over-irrigated  soil.  Some  varieties  are  affected  by  some  little  under- 
stood fruit  rots,  which  sometimes  cause  loss  locally.  Black  scale  is 
very  troublesome  in  foggy  coast  regions.  In  the  interior  it  gives  little 
trouble. 

Varieties.  Only  olives  large  enough  for  pickles  are  profitable. 
The  size  of  the  fruit  depends  on  the  variety,  the  location,  the  soil  and 
on  the  methods  of  pruning,  cultivation  and  irrigation  employed. 

Mission.  The  principal  and  standard  variety  of  California.  The 
fruit  is  large,  firm,  of  typical  olive  shape  and  deeply  colored  when 
ripe.  It  ripens  late  in  November  in  the  earliest  but  not  until  Feb- 
ruary in  the  later  localities.  The  tree  is  vigorous  and  bears  well  in 
most  localities.     There  is  much  variation  in  Mission  trees  and  it  is 


—  3  — 

important  that  stock  for  propagation  should  be  taken  only  from  trees 
of  known  good  performance.  It  is  preferred  by  the  pickle  manu- 
facturers because  their  methods  are  adapted  to  this  variety.  Its 
main  defect  is  its  late  and  irregular  ripening  which  exposes  it  to  injury 
from  frost  in  most  localities,  and  necessitates  several  pickings. 

Sevillano.  The  variety  from  which  the  largest  "Queen"  olives  of 
Spain  are  made.  When  ripe,  it  makes  excellent  black  pickles.  It 
resembles  the  Mission  in  shape,  color  and  flavor,  and  differs  from  it  in 
its  larger  fruit  and  narrower  leaves.  It  has  not  been  widely  tested, 
but  bears  well  in  some  places,  and  the  fruit  brings  a  large  price.  It 
ripens  early,  but  is  said  to  be  sensitive  to  frost. 

Manzanillo.  This  variety  has  been  planted  extensively.  The  fruit 
is  a  little  larger  than  that  of  the  Mission  and  deeply  colored.  Its  short 
apple-shape  is  considered  undesirable,  but  the  quality  of  the  ripe 
pickles  is  unexcelled.  Its  chief  merit  is  that  it  ripens  early.  It  bears 
well  in  favorable  locations,  but  fails  in  others.  It  is  subject  to  a  kind 
of  soft  rot  in  the  hotter  localities. 

Ascolano.  This  variety  has  very  large  fruit,  exceeding  even  the 
Sevillano.  It  has  been  planted  in  small  quantities  in  several  localities 
and  is  everywhere  reported  as  a  good  bearer.  The  fruit  is  of  the  shape 
and  size  of  a  French  prune.  It  contains  very  little  bitterness  or  color 
and  requires  special  care  in  pickling.  Some  large  plantings  of  this 
variety  have  been  made  lately. 

Other  varieties  producing  large  fruit,  but  little  tested,  are  Obliza, 
Macrocarpa,  Picholine  (true).  Others  sometimes  large  enough  for 
pickling  are  Columbella,  Regalis,  Gordal,  Atro-rubens,  Verdale,  Santa 
Caterina.  The  "Redding  Picholine"  is  a  small  seedling,  largely 
planted  by  mistake,  but  worthless  except  as  a  grafting  stock. 

If  more  than  one  variety  is  planted,  they  should  be  arranged  so 
that  they  can  be  harvested  separately.  The  utility  of  cross-pollination 
is  probable,  but  not  demonstrated.  Better  bearing  has  been  noted 
following  the  introduction  of  an  apiary  into  the  orchard. 

PICKLING. 

The  pickling  of  olives  involves  three  steps:  1.  Treatment  with  lye 
to  neutralize  the  acidity  and  bitterness.  2.  Repeated  soaking  in  water 
to  remove  the  excess  of  lye.  3.  Salting  by  soaking  in  brines  of  gradu- 
ally increasing  strengths. 

(1)  Neutralization.  Soak  the  olives  for  twelve  hours  in  a  solution 
made  by  dissolving  1^  pounds  of  caustic  potash  in  12  gallons  of  water. 
Very  bitter  olives  may  require  a  second  treatment  with  fresh  lye 
(some  Mission,  Manzanillo,  Sevillano)  ;  sweeter  olives  may  require  a 
weaker  lye  (Ascolano,  Columbella).  With  soft  olives,  1^  pounds  of 
salt  should  be  added  to  the  lye.  The  olives  should  be  kept  submerged 
by  means  of  a  floating  cover  and  the  lye  drawn  from  the  bottom  and 
poured  over  the  top  two  or  three  times  to  insure  equal  treatment. 


—  4  — 

(2)  Soaking.  When  by  examination  of  the  color  of  the  flesh  of  the 
olives,  it  is  found  that  the  lye  has  penetrated  nearly  to  the  pit,  they 
should  be  removed  to  pure  water.  This  water  is  renewed  at  least  once 
a  day  until  the  lye  is  removed,  which  requires  two  or  three  days. 
With  soft  olives,  a  brine  containing  about  two  pounds  of  salt  to 
twelve  gallons  of  water  should  be  used  for  removing  the  lye. 

(3)  Salting.  When  the  lye  and  most  of  the  bitterness  have  been 
removed  the  olives  should  be  placed  in  stronger  brine.  It  the  olives 
are  to  be  canned  or  bottled,  a  brine  containing  about  five  pounds  of 
salt  to  twelve  gallons  of  water  is  sufficiently  strong.  If  they  are  to.be 
kept  in  barrels  ten  or  twelve  pounds  of  salt  will  be  needed.  The 
olives  must  be  prepared  for  the  strong  brine  gradually  by  being 
placed  in  new  brines  every  three  to  four  days.  Each  brine  should  be 
about  two  per  cent  stronger  than  the  last. 

Precautions.  Strong  lye  tends  to  soften  the  fruit.  A  second 
treatment  in  weak  lye  is  better  for  bitter  olives  than  a  strong  lye. 
Salt  has  a  tendency  to  harden  the  fruit  and  can  be  used  to  counteract 
the  softening  effect  of  the  lye  with  very  ripe  olives.  Strong  brine  will 
shrink  and  shrivel  the  olives,  unless  they  are  prepared  for  it  by  solu- 
tions of  gradually  increasing  strengths. 

Color.  With  ripe  pickles,  the  object  is  to  have  the  color  as  uniform 
and  dark  as  possible.  Uniformity  is  obtained  by  pickling  each 
variety  by  itself,  by  having  the  fruit  as  evenly  ripe  as  possible  and  by 
exposing  the  olives  to  each  solution  in  as  uniform  a  manner  as  pos- 
sible. Spotting  comes  usually  from  unevenness  of  the  lye  treatment, 
and  especially  from  allowing  some  olives  to  float  on  the  surface. 
Depth  of  color  is  obtained  by  having  the  olives  thoroughly  ripe.  By 
exposing  the  olives  to  the  air  for  several  hours  between  the  various 
solutions,  both  the  depth  and  uniformity  of  the  color  are  increased  by 
oxidizing   and  browning  the  flesh. 

With  green  olives,  the  air  should  be  excluded  as  much  as  possible, 
until  the  final  brine  is  reached.  A  little  vinegar  improves  both  the 
color  and  flavor  of  green  olives.  Some  picklers  advise  the  addition 
also  of  a  few  bay  leaves. 


